External motor cut-off pwhawk

Hello, i want to find a easy solution to stop motors with external circuit in parallel ,my idea is just to link pwm signal with mosfet or transistor to the ground , I wonder if it might not destroy the pixhawk , in piaxhawk 1 hardware there is 220 ohms resistor in series with servo output , i can not find the pixhawak 4 detailed hardware ,it should be the same thing and it can work , I want your idea on the subject